// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_GPU_VT_VIDEO_ENCODE_ACCELERATOR_MAC_H_
#define MEDIA_GPU_VT_VIDEO_ENCODE_ACCELERATOR_MAC_H_

#include <deque>
#include <memory>

#include "base/bind.h"
#include "base/mac/scoped_cftyperef.h"
#include "base/memory/weak_ptr.h"
#include "base/single_thread_task_runner.h"
#include "base/threading/thread.h"
#include "base/threading/thread_checker.h"
#include "media/base/mac/videotoolbox_helpers.h"
#include "media/gpu/media_gpu_export.h"
#include "media/video/video_encode_accelerator.h"
#include "third_party/webrtc/common_video/include/bitrate_adjuster.h"

namespace media {

// VideoToolbox.framework implementation of the VideoEncodeAccelerator
// interface for MacOSX. VideoToolbox makes no guarantees that it is thread
// safe, so this object is pinned to the thread on which it is constructed.
class MEDIA_GPU_EXPORT VTVideoEncodeAccelerator
    : public VideoEncodeAccelerator {
public:
    VTVideoEncodeAccelerator();
    ~VTVideoEncodeAccelerator() override;

    // VideoEncodeAccelerator implementation.
    VideoEncodeAccelerator::SupportedProfiles GetSupportedProfiles() override;
    bool Initialize(VideoPixelFormat format,
        const gfx::Size& input_visible_size,
        VideoCodecProfile output_profile,
        uint32_t initial_bitrate,
        Client* client) override;
    void Encode(const scoped_refptr<VideoFrame>& frame,
        bool force_keyframe) override;
    void UseOutputBitstreamBuffer(const BitstreamBuffer& buffer) override;
    void RequestEncodingParametersChange(uint32_t bitrate,
        uint32_t framerate) override;
    void Destroy() override;

private:
    // Holds the associated data of a video frame being processed.
    struct InProgressFrameEncode;

    // Holds output buffers coming from the encoder.
    struct EncodeOutput;

    // Holds output buffers coming from the client ready to be filled.
    struct BitstreamBufferRef;

    // Encoding tasks to be run on |encoder_thread_|.
    void EncodeTask(const scoped_refptr<VideoFrame>& frame, bool force_keyframe);
    void UseOutputBitstreamBufferTask(
        std::unique_ptr<BitstreamBufferRef> buffer_ref);
    void RequestEncodingParametersChangeTask(uint32_t bitrate,
        uint32_t framerate);
    void DestroyTask();

    // Helper function to set bitrate.
    void SetAdjustedBitrate(int32_t bitrate);

    // Helper function to notify the client of an error on |client_task_runner_|.
    void NotifyError(VideoEncodeAccelerator::Error error);

    // Compression session callback function to handle compressed frames.
    static void CompressionCallback(void* encoder_opaque,
        void* request_opaque,
        OSStatus status,
        VTEncodeInfoFlags info,
        CMSampleBufferRef sbuf);
    void CompressionCallbackTask(OSStatus status,
        std::unique_ptr<EncodeOutput> encode_output);

    // Copy CMSampleBuffer into a BitstreamBuffer and return it to the |client_|.
    void ReturnBitstreamBuffer(
        std::unique_ptr<EncodeOutput> encode_output,
        std::unique_ptr<VTVideoEncodeAccelerator::BitstreamBufferRef> buffer_ref);

    // Reset the encoder's compression session by destroying the existing one
    // using DestroyCompressionSession() and creating a new one. The new session
    // is configured using ConfigureCompressionSession().
    bool ResetCompressionSession();

    // Create a compression session, with HW encoder enforced if
    // |require_hw_encoding| is set.
    bool CreateCompressionSession(
        base::ScopedCFTypeRef<CFDictionaryRef> attributes,
        const gfx::Size& input_size,
        bool require_hw_encoding);

    // Configure the current compression session using current encoder settings.
    bool ConfigureCompressionSession();

    // Destroy the current compression session if any. Blocks until all pending
    // frames have been flushed out (similar to EmitFrames without doing any
    // encoding work).
    void DestroyCompressionSession();

    base::ScopedCFTypeRef<VTCompressionSessionRef> compression_session_;

    gfx::Size input_visible_size_;
    size_t bitstream_buffer_size_;
    int32_t frame_rate_;
    int32_t initial_bitrate_;
    int32_t target_bitrate_;
    int32_t encoder_set_bitrate_;

    // Bitrate adjuster used to fix VideoToolbox's inconsistent bitrate issues.
    webrtc::BitrateAdjuster bitrate_adjuster_;

    // Bitstream buffers ready to be used to return encoded output as a FIFO.
    std::deque<std::unique_ptr<BitstreamBufferRef>> bitstream_buffer_queue_;

    // EncodeOutput needs to be copied into a BitstreamBufferRef as a FIFO.
    std::deque<std::unique_ptr<EncodeOutput>> encoder_output_queue_;

    // Our original calling task runner for the child thread.
    const scoped_refptr<base::SingleThreadTaskRunner> client_task_runner_;

    // To expose client callbacks from VideoEncodeAccelerator.
    // NOTE: all calls to this object *MUST* be executed on
    // |client_task_runner_|.
    base::WeakPtr<Client> client_;
    std::unique_ptr<base::WeakPtrFactory<Client>> client_ptr_factory_;

    // Thread checker to enforce that this object is used on a specific thread.
    // It is pinned on |client_task_runner_| thread.
    base::ThreadChecker thread_checker_;

    // This thread services tasks posted from the VEA API entry points by the
    // GPU child thread and CompressionCallback() posted from device thread.
    base::Thread encoder_thread_;
    scoped_refptr<base::SingleThreadTaskRunner> encoder_thread_task_runner_;

    // Declared last to ensure that all weak pointers are invalidated before
    // other destructors run.
    base::WeakPtr<VTVideoEncodeAccelerator> encoder_weak_ptr_;
    base::WeakPtrFactory<VTVideoEncodeAccelerator> encoder_task_weak_factory_;

    DISALLOW_COPY_AND_ASSIGN(VTVideoEncodeAccelerator);
};

} // namespace media

#endif // MEDIA_GPU_VT_VIDEO_ENCODE_ACCELERATOR_MAC_H_
